To develop a nonradioactive breath test using the stable isotope 13C Spirulina for measuring gastric emptying of solids. To assess the correlation between t 1/2 obtained from 13C Spirulina breath test and t 1/2 of the simultaneously performed scintigraphic technique in health subjects. This study will most likely validate a new method to noninvasively measure gastric emptying using stable isotopes. It has immense potential for studies of nausea, vomiting and abdominal symptoms in pediatric and obstetric practice and in community or epidemiologic studies.